build(deps): bump MessageBox.Avalonia from 1.5.5 to 1.6.0 in /Sample (#553)

Bumps [MessageBox.Avalonia](https://github.com/CreateLab/MessageBox.Avalonia) from 1.5.5 to 1.6.0.
- [Release notes](https://github.com/CreateLab/MessageBox.Avalonia/releases)
- [Commits](https://github.com/CreateLab/MessageBox.Avalonia/commits)

---
updated-dependencies:
- dependency-name: MessageBox.Avalonia
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

Sample/SextantSample.Avalonia/SextantSample.Avalonia.csproj

@@ -5,7 +5,7 @@
     </PropertyGroup>
     <ItemGroup>
         <PackageReference Include="Citrus.Avalonia" Version="1.5.1" />
-        <PackageReference Include="MessageBox.Avalonia" Version="1.5.5" />
+        <PackageReference Include="MessageBox.Avalonia" Version="1.6.0" />
     </ItemGroup>
     <ItemGroup>
         <Compile Update="**\*.xaml.cs">